55 research outputs found
A Logical Design Methodology for Relational Databases Using the Extended ER Model
https://deepblue.lib.umich.edu/bitstream/2027.42/154152/1/39015099114723.pd
A knowledge-based approach to multiple query processing
The collective processing of multiple queries in a database system has recently received renewed attention due to its capability of improving the overall performance of a database system and its applicability to the design of knowledge-based expert systems and extensible database systems. A new multiple query processing strategy is presented which utilizes semantic knowledge on data integrity and information on predicate conditions of the access paths (plans) of queries. The processing of multiple queries is accomplished by the utilization of subset relationships between intermediate results of query executions, which are inferred employing both semantic and logical information. Given a set of fixed order access plans, the A* algorithm is used to find the set of reformulated access plans which is optimal for a given collection of semantic knowledge.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28071/1/0000514.pd
From Cooperative Scans to Predictive Buffer Management
In analytical applications, database systems often need to sustain workloads
with multiple concurrent scans hitting the same table. The Cooperative Scans
(CScans) framework, which introduces an Active Buffer Manager (ABM) component
into the database architecture, has been the most effective and elaborate
response to this problem, and was initially developed in the X100 research
prototype. We now report on the the experiences of integrating Cooperative
Scans into its industrial-strength successor, the Vectorwise database product.
During this implementation we invented a simpler optimization of concurrent
scan buffer management, called Predictive Buffer Management (PBM). PBM is based
on the observation that in a workload with long-running scans, the buffer
manager has quite a bit of information on the workload in the immediate future,
such that an approximation of the ideal OPT algorithm becomes feasible. In the
evaluation on both synthetic benchmarks as well as a TPC-H throughput run we
compare the benefits of naive buffer management (LRU) versus CScans, PBM and
OPT; showing that PBM achieves benefits close to Cooperative Scans, while
incurring much lower architectural impact.Comment: VLDB201
Linking data and BPMN processes to achieve executable models
We describe a formally well founded approach to link data and processes conceptually, based on adopting UML class diagrams to represent data, and BPMN to represent the process. The UML class diagram together with a set of additional process variables, called Artifact, form the information model of the process. All activities of the BPMN process refer to such an information model by means of OCL operation contracts. We show that the resulting semantics while abstract is fully executable. We also provide an implementation of the executor.Peer ReviewedPostprint (author's final draft
Case Study: How Modeling Revealed Serious Performance Problems in Distributed (DCE) Systems
http://deepblue.lib.umich.edu/bitstream/2027.42/107930/1/citi-tr-96-1.pd
Performance of DCE RPC
http://deepblue.lib.umich.edu/bitstream/2027.42/107932/1/citi-tr-95-2.pd
Performance Modeling of the Distributed Computing Environment
http://deepblue.lib.umich.edu/bitstream/2027.42/107936/1/citi-tr-95-6.pd
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